Disposable guide device for spinal surgery

ABSTRACT

A disposable guide device for spinal surgery comprises two tubular guide bodies extending along respective main axes between a proximal end and a distal end to guide a surgical operation on a vertebra of a patient, a plurality of support feet projecting laterally relative to each guide body, near said proximal end, each defining a contact area configured to abut on a side of the spinous process or on a lamina or facet or transverse process of the vertebra of the patient, in a mating configuration, at least one junction element extending between the guide bodies, starting from the respective distal ends, in order to space them from each other, wherein the guide bodies are oriented so that the proximal ends are more distant from each other with respect to the distal ends.

The present invention relates to the technical field of orthopaedicsurgery. More specifically, the invention relates to a disposable guidedevice for spinal surgery, used to help the surgeon to perform somedelicate steps of surgical procedures, such as for example bone drillsand cuts, which can be pre-operatively planned by computer-aidedtechnologies.

The guide devices are disposable templates, which are typicallycustomized, i.e. designed to match the bone anatomy derived fromcomputed tomography images of a given patient. Such devices arecurrently employed in several fields of orthopaedic surgery, includingspinal surgery.

In this field, the guide devices are mainly employed to help the surgeonduring pedicle screw insertion, so that the screw can be insertedaccording to a pre-planned optimal axis of the screw.

However, these devices may be used in spinal surgery for other purposes;for instance as cutting guides during PSO (pedicle substractionosteotomies), laminotomy or facectomies.

In general, the guide devices are provided with one or more guide bodiesand one or more contact elements adapted to mate with the vertebrae ofthe patient in a stable and well defined configuration. In order toachieve this goal, large contact areas between the guide device and thepatient's bone structure are required.

Therefore, before positioning the guide, the surgeon must wash thesurrounding tissue away from a large area of the bone, and in some casescut the ligaments. This often proves to be a difficult and costly taskin terms of time, and can lead to complications and lengthening of thepatient's hospitalization.

In addition, the residual tissue that cannot be removed by the surgeoncan result in slipping and deviation of the guide device, whichsometimes leads to incorrect or suboptimal positioning of the pediclescrews or bone resections.

But not only, the step of placing the guide in contact with the boneoccurs after a preliminary step of inserting and positioning the guide,which is also made very difficult by the poor ergonomics of the device.

In view of the foregoing, the technical problem underlying the presentinvention is to provide a disposable guide device for spinal surgery,which can be easily handled and coupled in a stable and unique manner tothe vertebrae of a patient.

The aforementioned technical problem is solved by means of a guidedevice for spinal surgery, according to claim 1.

In particular, the disposable guide device for spinal surgery comprisestwo tubular guide bodies extending along respective main axes from aproximal end to a distal end to guide a surgical operation on a vertebraof a patient.

In order to promote the stability of the device, a plurality of supportfeet is provided, which project laterally relative to each guide body,near said proximal end, each defining a contact area configured to abuton a respective portion of the vertebra; preferably, this portion is oneside of the spinous process, a lamina, a facet, an articular process, ora transverse process of the patient's vertebra.

In addition, the device comprises at least one junction elementextending between said guide bodies, starting from the respective distalends, in order to space them from each other.

According to one aspect of the present invention, the guide bodies areoriented so that the proximal ends are more distant from each other withrespect to the distal ends.

In certain embodiments, the junction element comprises at least onecurved handle extending from both of the guide bodies, away from them,up to a top intermediate portion.

In order to optimize and facilitate the positioning/insertion steps, thehandle is shaped so that a projection of its intermediate portion oneach main axis of the guide bodies falls outside of the footprint ofsaid guide bodies.

In other words, the handle's inclination and extension are such that theprojection of its intermediate portion on each main axis has a distancefrom the proximal end greater than the distance between the proximal endand the distal end.

Advantageously, this facilitates the surgeon's gripping and manoeuvringof the device, particularly thanks to the arm that allows, with smallmovements of the hand, (relatively) large movements of the feet of thedevice.

In other embodiments, the junction element is preferably defined by atleast one junction bridge between said two guide bodies provided with atleast one central portion arranged astride a spinous process of thevertebra to be operated.

Preferably, the junction bridge is shaped so that its central portion isdesigned to pass over, with or without contact, the spinous process,thereby making the positioning of the device easier.

It should be noted that, in the preferred embodiments, the junctionelements are two, i.e. the handle as well as the bridge.

Preferably, the bridge and the handle extend from the guide bodies awayfrom each other. In other words, the bridge and the handle protrude fromopposite sides of the guide bodies.

Advantageously, this configuration is particularly well adapted to thetypical conformation of the cervical vertebrae, further facilitating agood positioning of the device.

Further features and advantages of the patient-specific navigationalguide according to the invention will become more apparent from thedescription, provided hereinbelow, of a number of embodiments describedby way of non-limiting example with reference to the accompanyingdrawings, wherein:

FIG. 1 shows a perspective view of a disposable guide device for spinalsurgery according to the present invention, coupled to a cervicalvertebra of the patient;

FIGS. from 2 to 5 show several views of the disposable guide device ofFIG. 1;

FIG. 6 shows an alternative embodiment of the guide device of FIGS. 1-5,wherein the spinous process is schematically shown in contact with thebridge.

With reference to the accompanying figures, the numeral 1 indicates aguide device for spinal surgery according to the present invention.

In particular, the figures show a device specifically designed forsurgery on a cervical vertebra 100.

As can be readily recognized in these figures, the guide device 1comprises two tubular guide bodies 2.

These guide bodies 2 are connected to each other by means of a junctionelement 3 (or supporting frame).

More precisely, each guide body 2 extends along its main axis “A”between a distal end 2 b and a proximal end 2 a.

Note that the terms “distal” and “proximal”, as used herein, refer tothe position of an element (e.g. end) with respect to the vertebral bodyof the vertebra 100.

Therefore, each tubular guide body 2 houses an insertion duct 4extending with substantial continuity between the distal end 2 b and theproximal end 2 a.

In other words, the duct 4 extends between a distal opening 4 b, formedin the distal end 2 b of the guide body 2, and a proximal opening 4 a,formed in the proximal end 2 a of the guide body 2.

It should be noted that the ducts 4 extend along the aforementioned mainaxes “A” of the guide bodies 2.

Therefore, the ducts 4 define respective insertion axes for two pediclescrews, which can be inserted in the vertebra 100 according to apre-operatively planned angle.

Thus, the distal opening 4 b corresponds to an access opening of thesurgical instrument, while the proximal opening 4 a faces the patient'svertebra 100, in the vicinity of the same.

Therefore, the diameter of the duct 4 is such as to allow the insertionof a Kirschner wire. In use, the Kirschner wire is implanted into thebone and, when the device 1 is removed, is used to guide a polyaxialscrew, which runs along the wire in order to touch the bone at thepredetermined point and be implanted. The inner diameter of the ducts 4of the tubular guide members 2 can also be large enough to allow thepassage of a polyaxial screw. Said inner diameter can be selected from3-18 mm, 3-12 mm, 3-9 mm, 3-6 mm.

According to one aspect of the present invention, the guide bodies 2 areoriented so that the proximal ends 2 a are more distant from each otherwith respect to the distal ends 2 b.

In other words, the respective main axes “A” of the guide bodies 2 areoriented, starting from the distal ends 2 b, away from each other.

Therefore, the guide device 1 according to the present inventionpreferably has a “diverging” configuration, in which the guide bodies 2widen in the proximal region.

Advantageously, this simplifies the positioning of the device 1, thusreducing the space the surgeon needs for insertion.

As mentioned previously, a junction element 3 is provided between thetwo guide bodies 2.

Preferably, said at least one junction element 3 extends transversely tothe two guide bodies 2 to place them in rigid connection.

More preferably, the junction element 3 is placed in the vicinity of thedistal end 2 b of the guide bodies 2.

This junction element 3 is therefore a (preferably non-straight)crossbar extending between the two guide bodies so as to space them.

Therefore, both the distal ends 2 b and the proximal ends 2 b of theguide bodies 2 are spaced from each other by a distance at least equalto a volume housing a spinous process 101 of the vertebra 100 to beoperated.

According to a further aspect of the present invention, the junctionelement 3 comprises a curved handle 5 extending from both of the guidebodies 2, away from them, up to a top intermediate portion 5 a.

In particular, the handle 5 is shaped so that a projection of itsintermediate portion 5 a on each main axis “A” of the guide bodies 2falls outside of the footprint of said guide bodies.

Preferably, the handle 5 is thus a U- or V-shaped, in any case curved,element, such that the concavity defined by the top portion 5 a facesthe guide bodies 2.

Hence, the handle 5 comprises two end portions 5 b extending from thedistal ends 2 b of the guide bodies 2 up to the intermediate portion 2a, preferably approaching each other.

Preferably, said handle 5 extends away from the guide bodies 2, with apredetermined inclination with respect to the main axis “A”.

More precisely, with reference to a cross section plane “B” (FIG. 2)passing through the intermediate portion 5 a of the handle 5, aprojection of the main axis “A” on said section plane “B” defines afirst angle α with a projection “Pm”, on said section plane “B”, of amedian line of said handle 5.

The main axis “A” is preferably inclined with respect to the sectionplane by an angle γ comprised between 0° and 35°, more preferablybetween 10° and 20°.

As regards the first angle α, preferably, the first angle is comprisedbetween 20° and 60°.

According to a further aspect of the present invention, the junctionelement 3 comprises at least one junction bridge 6 between said twoguide bodies 2 provided with at least one central portion 6 a designedto pass over the spinous process 101 of the vertebra 100 to be operated.

More precisely, the central portion 6 a can pass over the spinousprocess without contact (FIG. 1) or with contact, i.e. partially restingon it (FIG. 6).

The bridge 6 preferably comprises at least two arms 6 b, each extendingfrom a guide member 2; the central portion 6 a connects the two arms 6 bto each other. The arms 6 b are preferably oriented in mutual approach.

It should be noted that, preferably, the arms 6 b have, in the plane ofFIG. 3, an inclination with respect to a median axis of the centralportion 6 a comprised between 0° and 80°.

Therefore, the arms 6 b have an inclination substantially comprisedbetween approximately 0° and 80° with respect to a line joining the twoducts 4 (lying in a plane parallel to the plane of FIG. 3).

Advantageously, in this way, with the same entry point of the screw,i.e. keeping the position of the proximal opening 4 a unchanged, bymodifying the inclination of the arms 6 b, the inclination of the ducts4, i.e. of the guide bodies 2, can be varied correspondingly.

The central portion 6 a of the bridge 6 is therefore designed to passover the spinous process 101 of the vertebra 100 to be operated.

For this purpose, said central portion 6 a has the shape of an inverted“U” internally defining a housing seat for the spinous process 101 ofthe vertebra 100.

Preferably, the central portion 6 a of the bridge 6 comprises at leasttwo lateral sides and a top wall defining said U-shape. The lateralsides are connected to the arms 6 b.

In the preferred embodiment, the lateral sides and the top wall aresubstantially orthogonal and define a square configuration of thehousing volume.

Advantageously, this makes the piece very simple and economical tomanufacture.

It should be noted that the central portion 6 a can take on variousconfigurations depending on the application.

According to a first embodiment, shown in FIGS. 1-5, the housing seat isopen in the cranial-caudal direction in order to prevent the patient'sligaments from being excised before placing the guide in the matingconfiguration (open profile).

As an alternative, not shown, the housing seat can be closed in thecranial-caudal direction by means of a septum or two septa that connectboth lateral sides of the central portion 6 a, forming, respectively, asemi-open or closed profile surrounding the spinous process 101, so asto ensure excellent stability to the operative guide 1.

With reference to a section plane “B” passing through the centralportion of the bridge 6 (FIG. 2), a projection of the main axis “A” onsaid section plane “B” defines a second angle β with a projection “Pb”,on said section plane “B”, of a median line of said bridge 6.

Preferably, the second angle β is comprised between 20° and 60°.

In the preferred embodiment shown in FIGS. 1-5, the device 1 comprisesboth the handle 5 and the junction bridge 6, each defining a junctionelement 3.

Therefore, preferably, the device 1 comprises at least two junctionelements 3.

Preferably, the bridge 6 and the handle 5 are arranged on opposite sidesof the guide bodies 2.

In other words, the bridge 6 and the handle 5 extend from said guidebodies 2 away from each other.

Preferably, the bridge 6 and the handle 5 are shaped so that the firstangle α is greater than the second angle β.

In this respect, it should be noted that the section plane “B” passesboth through said intermediate portion 5 a of the handle 5 and thecentral portion 6 a of the bridge 6.

In particular, preferably, the sum of said first angle α and said secondangle β is comprised between 45° and 100°.

Moreover, the handle 5 and the bridge 6 extend in such a way that thecentral portion 6 a of the bridge 6 is proximal to the guide bodies 2with respect to the intermediate portion 5 a of the handle 5.

In other words, the handle 5 protrudes laterally relative to the guidebodies 2 in a more significant way compared to the bridge 6.

In addition, the handle 5 protrudes externally at the distal end 2 b ofthe guide bodies 2 to a greater extent compared to the bridge.

In order to promote the stability of the device 1, it comprises aplurality of support feet 7, which project laterally relative to eachguide body 2, near said proximal end 2 a, each defining a contact areaconfigured to abut on a respective portion of the vertebra 100.

Preferably, said portion is one side of the spinous process 101, alamina 104, an articular process 102 or a transverse process 103 of thepatient's vertebra 100.

Said feet 7 are pre-operatively planned by means of computer-aideddesign tools, on a three-dimensional model of the bone structuredeveloped from a three-dimensional image (e.g., computed tomographyimage/magnetic resonance) of the patient. Therefore, each of the feet 7(as well as the orientation of the guide bodies 2) is designed so thatit uniquely matches the bone structure of the patient.

Preferably, the plurality of feet 7 comprises at least two feet for eachguide body 2.

It should be noted that, preferably, the feet associated with each guidebody are angularly spaced from one another so as to rest on thedifferent portions of the vertebra in an “accurate” manner, thusreducing the overall contact surface and increasing the number of“isolated” contact points.

More precisely, each guide body 2 preferably comprises at least onefirst foot 8 defining a support element on one side of the spinousprocess 101 of the patient's vertebra 100.

Said first foot 8 preferably extends from a guide body 2 and is at leastin part directed toward the other guide body 2.

Said first feet 8 are thus defined by protuberances 8 a extending from aside wall of the guide bodies 2 (preferably, but not necessarily,approaching each other) and with a predetermined inclination withrespect to the main axis “A”.

Preferably, such protuberances 8 a are substantially straight andinclined with respect to the guide body 2.

Each protuberance 8 a ends with a contact face 8 b shapedcomplementarily to the surface of the side of the spinous process 101 ofthe patient's vertebra 100.

More precisely, the first feet 8 extend along respective main directionsdefining acute angles with the portion of the main axis “A” includedbetween a point of intersection with said main direction and theproximal end of the guide body 2.

In addition, each guide body 2 comprises at least one second foot 9oriented away from the other guide body 2 and defining a support elementon an articular process 102 (or transverse process 103) of the patient'svertebra 100.

These second feet 9 are substantially L-shaped.

More precisely, each second foot 9 preferably comprises a radial portion9 a and a contact portion 9 b.

The radial portion 9 a extends away from the respective guide body 2along a direction substantially orthogonal to the main axis “A”.

The contact portion 9 b extends from a free end of the radial portion 9a transversely thereto; more precisely, such a contact portion extendsfrom the radial portion 9 a toward the proximal end 2 a.

Said contact portion 9 b ends, in turn, with an abutment face 9 c shapedcomplementarily to the surface of the respective articular process 102(or transverse process 103) of the patient's vertebra 100.

Advantageously, in this way, it is possible to obtain a particularlystrong resting area even without the need for extensive restingsurfaces.

In a preferred embodiment, the guide body 2 further comprises anenlarged portion 10 located near the proximal end 2 a and defining asupport base on the lamina 104 of the patient's vertebra 100.

In other words, the enlarged portion 10 is defined by an (at leastpartial) enlargement of the section in the vicinity of the proximal end2 a.

In this respect, it should be noted that, preferably, the proximal end 2a of each guide member 2 has at least one resting face 10 a shapedcomplementarily to the surface of the respective lamina 104 of thepatient's vertebra 100.

More precisely, the proximal end 2 a of the guide bodies 2 has a taperedhalf 11 a, such as to facilitate the positioning and visualization bythe surgeon, and a substantially flat half 11 b, corresponding to saidresting face 10 a of the enlarged portion 10.

Advantageously, this allows the stability of the device 1 to bemaximized without increasing the encumbrance.

In certain embodiments, each guide body 2 is also provided with afurther contact portion 12, also projecting laterally to the guide body2 near the proximal end 2 a and configured to abut on a transverseprocess 103 of the vertebra 100.

Preferably, said further contact portion 12 is also L-shaped, thereforeprovided with a radial portion 12 a and a contact portion 12 b directedtoward the proximal end 2 a of the guide body 2.

The contact portion 12 b ends, in turn, with an abutment face 12 cshaped complementarily to the surface of the respective transverseprocess 103 of the patient's vertebra 100.

The invention achieves the intended objects and attains importantadvantages.

In fact, the provision of a device with “diverging” guide bodiesfacilitates the positioning thereof, which is further facilitated by thepresence of a handle protruding outside of the footprint of said guidebodies.

Moreover, the presence of numerous feet or contact portions angularlyspaced in the vicinity of the proximal end of the guide bodies is evenmore advantageous in terms of stability.

1. A disposable guide device for spinal surgery, comprising: two tubularguide bodies extending along respective main axes between a proximal endand a distal end to guide a surgical operation on a vertebra of apatient; a plurality of support feet projecting laterally relative toeach guide body, near said proximal end, each defining a contact areaconfigured to abut on a side of the spinous process or on a lamina orfacet or transverse process of the vertebra of the patient, in a matingconfiguration; at least one junction element extending between saidguide bodies, starting from the respective distal ends, in order tospace them from each other; characterised in that the guide bodies areoriented so that the proximal ends are more distant from each other withrespect to the distal ends.
 2. The guide device according to claim 1,characterised in that the respective main axes of the guide bodies areoriented, starting from the distal ends, away from each other.
 3. Theguide device according to claim 1, characterised in that at least onejunction element comprises a curved handle extending from both of theguide bodies, away from them, up to a top intermediate portion.
 4. Thedevice according to claim 3, characterised in that a projection of saidintermediate portion of the handle on each main axis of the guide bodiesfalls outside of the footprint of said guide bodies.
 5. The guide deviceaccording to claim 3, characterised in that, with reference to a crosssection plane passing through said intermediate portion of the handle, aprojection of the main axis on said section plane defines a first anglewith a projection, on said section plane, of a median line of saidhandle.
 6. The guide device according to claim 5, characterised in thatsaid first angle is comprised between 20° and 60°.
 7. The guide deviceaccording to claim 1, characterised in that said at least one junctionelement comprises at least one junction bridge between said two guidebodies provided with at least one central portion designed to pass over,with or without contact, a spinous process of the vertebra to beoperated.
 8. The guide device according to claim 7, characterised inthat, with reference to a cross section plane passing through saidcentral portion of the bridge, a projection of the main axis on saidsection plane defines a second angle with a projection, on said sectionplane, of a median line of said bridge.
 9. The device according to claim8, characterised in that said second angle is comprised between 20° and60°.
 10. The guide device according to claim 3, characterised in that itcomprises two junction elements defined respectively by said handle andsaid bridge.
 11. The guide device according to claim 10, characterisedin that said bridge and said handle extend from said guide bodies awayfrom each other.
 12. The guide device according to claim 5,characterised in that said section plane passes through saidintermediate portion of the handle and said central portion of thebridge.
 13. The guide device according to claim 5, characterised in thatsaid first angle is greater than said second angle.
 14. The guide deviceaccording to claim 5, characterised in that the sum of said first angleand said second angle is comprised between 45° and 100°.
 15. The guidedevice according to claim 10, characterised in that the central portionof the bridge is proximal to the guide elements with respect to theintermediate portion of the handle.
 16. The guide device according toclaim 1, characterised in that said tubular guide bodies have respectivetubular walls extending with continuity between said proximal end andsaid distal end.
 17. The guide device according to claim 1,characterised in that each guide body comprises: at least one first footdefining a support element on one side of the spinous process of thevertebra of the patient; at least one second foot oriented away from theother guide body and defining a support element on an articular processor transverse process of the vertebra of the patient.
 18. The guidedevice according to claim 17, characterised in that each first foot isdefined by a protuberance extending from a side wall of the respectiveguide body with a predetermined inclination with respect to the mainaxis.
 19. The guide device according to claim 17, characterised in thatsaid second foot is substantially L-shaped.
 20. The guide deviceaccording to claim 19, characterised in that said second foot isprovided with: a radial portion extending away from the respective guidebody along a direction substantially orthogonal to the main axis and acontact portion extending from a free end of the radial portiontransversely thereto.
 21. The guide device according to claim 20,characterised in that said contact portion extends from the radialportion towards the proximal end of the guide body.
 22. The guide deviceaccording to claim 1, characterised in that each guide body comprises anenlarged portion near the proximal opening and defining a support baseon the lamina of the vertebra of the patient.